Method

Put the rice and 275ml water in a pan. Bring to the boil. Cook for 10 mins, then cover with a lid and take off the heat. Leave to stand, covered tightly, for 30 mins, then gently fluff with a fork and stir in the rice vinegar.

Put the sesame seeds on a plate. Brush both sides of the tuna with oil and press one side of each steak into the sesame seeds.

Heat a griddle pan or frying pan on a high setting. Sear the tuna steaks for 1 min on each side, or 2 mins on each side if you prefer it well done. Once seared, remove the tuna steaks, place on a chopping board and slice into thin strips.

Stir the ginger into the soy sauce in a small bowl. Divide the rice between 4 serving bowls and arrange the tuna, radishes, avocado and cucumber around the edges.

Top with the spring onions and chillies, if using. Serve with the ginger-soy dipping sauce on the side.